Miter boxes known in the art and offered commercially tend to be of relatively complex and expensive construction. To the extent that low-cost miter boxes are available, moreover, they often permit cutting at only a limited number of fixed angular positions, such as 22.5xc2x0, 45xc2x0, and 90xc2x0; it is of course commonly necessary to cut at angles other than those that may be established, and the limited capability such miter boxes therefore represents a serious deficiency. Low-cost miter boxes also generally lack a convenient and/or simple clamping arrangement, and may require the user to hold the workpiece manually during the cutting operation.
Representative of the prior art in the filed of the invention is Englehard U.S. Pat. No. 401,423 and Soukup U.S. Pat. No. 477,233, each of which provides a miter box that enables cutting throughout a range of angles. Erisoty et al. U.S. Pat. Des. No. 406,035 provides a low-cost miter box having a locking mechanism for securing the workpiece.
A need remains for a miter box that is of relatively incomplex design, inexpensive manufacture, and convenient to use, and that nevertheless enables cutting at virtually any angle, and it is a broad object of the present invention to provide such a miter box.
More specific objects of the invention are to provide such a miter box comprised of a minimal number of readily assembled and disassembled components, and that lends itself to manufacture, at least in significant part, from a synthetic resinous material using conventional molding techniques.
A further specific object of the invention is to provide such a miter box having an integrated clamping arrangement that is capable of easily and effectively securing workpieces of a wide range of thicknesses.
It has now been found that at least certain of the foregoing and related objects of the invention are attained by the provision of a miter box adapted for use for making cuts at each of a multiplicity of angles, and including a base and a generally U-shaped saw guide assembled therewith. The base is comprised of a table having a generally planar upper surface, an effectively circular passage extending on a axis normal to the upper surface of the table, and a forward edge portion on the table spaced from the passage; means is provided for supporting the table in an elevated position. The saw guide is comprised of a beam or arm, an upstanding pivot post adjacent the rearward end of the beam and pivotably engaged in the passage of the base, and an upstanding guide piece adjacent the forward end of the table; at least a portion of the length of the pivot post is of circular cross section to enable such pivotable engagement. The beam extends radially, in the space beneath the table, and is of such length as to dispose the guide piece adjacent the forward edge portion of the table. Both the pivot post and also the guide piece are slotted for cooperatively receiving the blade of a saw for reciprocal and longitudinal movement, and pivoting of the saw guide enables a saw so mounted to be aligned on any radius (within the range of movement) extending from the axis of the base passage.
In most embodiments the forward edge portion of the miter box table will be arcuate, and formed to extend circumferentially and concentrically with the circular passage. Indicia will usually be provided to afford visual references for selective angular positioning of the saw guide (and of course a mounted saw), relative to the base; such indicia may be printed on the surface and/or may constitute radial depressions formed into the surface to accommodate the cutting edge of the saw blade.
A member mounted on the saw guide and movable between positions of fixed engagement with and disengagement from the table may be provided for securing the saw guide in selected angular positions, such a securing member typically being of elongate form and mounted for movement (such as by threaded interengagement) on its longitudinal axis. The tip on one end of the securing member will generally be disposed to engage fixedly the forward edge portion of the table, and the securing member will desirably be oriented with a slight incline, in the direction of the table, so as to avoid interference with movement of a mounted saw. A plurality of discrete locking elements may be disposed at angularly spaced locations along the forward edge portion of the table, each coacting with the securing member for affixing the saw guide at a selected angular position.
The base of the miter box will normally include an upstanding fence member having portions disposed substantially diametrically to opposite sides of the circular passage through the base, thereby to provide a back supporting surface having elements in a plane substantially perpendicular to the plane in which the upper surface of the table lies. In such embodiments the pivot post will desirably be cylindrical along at least most of its length, with the fence member portions defining effectively a cylindrical bore which provides, at least in part, the passage in which the post is pivotably received and engaged.
The miter box will most desirably incorporate means for clamping a workpiece against the fence member. Such means will preferably define at least a first channel recessed into the upper surface of the table, a lug piece dimensioned and configured to seat in the channel at each of a multiplicity of locations along its length, and a clamping piece mounted on the lug piece for rotation about an axis normal to the plane of the upper surface of the table. The channel has a proximal end near the fence member and a remote distal end, and it is defined by shaped opposite sidewalls which substantially replicate one another and are characterized by a multiplicity of substantially identical structural elements spaced regularly along its length and projecting inwardly toward its center line. The opposite lateral surfaces of the lug piece are formed with structural features for matingly engaging the sidewalls of the channel and effectively locking it against displacement therealong. At least one lobe portion projects from the clamping piece, and has a bearing surface disposed for being brought, by rotation of the clamping piece, into clamping engagement with a workpiece supported against the back supporting surface of the fence member when the lug piece is seated in the channel at a proximate location.
In certain embodiments the structural elements of the channel-defining sidewalls will be symmetrical about centerlines through their apices, and the elements of one of the sidewalls will be offset, along the length of the channel, from the like structural elements of the other sidewall by a distance that is less than the pitch distance between adjacent apices (typically, half the distance); the mating structural features on the opposite lateral surfaces of the cooperating lug piece will have effectively the same relative offset. Such construction permits the lug piece to engagingly seat in the channel in end-for-end inverted orientations, with the position of the lug piece thereby being shifted somewhat along the length of the channel.
The clamping piece will also advantageously have two opposite ends, each providing a lobe portion with a bearing surface thereon, the clamping piece and lug piece having means for coupling them for relative rotation about an axis that is eccentric to a midpoint between the bearing surfaces. The means for coupling will conveniently comprise a pin projecting from one of the pieces into an aperture formed in the other piece, the aperture being dimensioned to receive the pin, desirably in snug interengagement, and the pin and/or the aperture being disposed on the eccentric axis of the clamping piece.
The channel formed into the table surface will usually extend along a substantially rectilinear axis, which axis will desirably be generally normal to the plane of the back supporting surface of the fence member. The sidewalls of the channel will typically be of scalloped or undulant, sawtooth, or square tooth character. In most instances the channel-defining means will define a second such channel, with an additional lug piece and an additional clamping piece being provided for functioning cooperatively with one another in the manner described. The two channels will normally be spaced laterally from one another to opposite sides of the axis of the circular passage through the base, and the portion of the table lying forwardly of the circular passage will usually be substantially semicircular.